1. Field of the Invention
The present invention relates to a control and a transmission of a straddle type vehicle.
2. Description of Related Art
In a conventional electronically controlled continuously variable transmission (ECVT), a gear ratio is automatically changed based on a gear ratio map indicating relationships among vehicle speeds, engine speeds (accelerator openings) and gear ratios. Accordingly, vehicles incorporating an ECVT do not require any gear change or clutch operations by a rider. Therefore, ECVTs are incorporated in various vehicles.
In a vehicle incorporating an ECVT, however, a rider cannot optionally change gear ratios from the settings in the gear ratio map. Hence, the rider has difficulty effectively activating an engine brake more strongly than that given by the gear ratio map.
In a vehicle incorporating an ECVT, it is also difficult to make a so-called kick down operation whereby a shift down operation is intentionally made more greatly than normal to increase acceleration of the vehicle, for example, when passing another vehicle.
A vehicle incorporating an ECVT has been proposed whereby both the so-called AT mode, in which gear ratios can be continuously and automatically changed, and the so-called MT mode, in which gear ratios can be changed optionally by the rider, are selectable. For example, JP-B-2950957 proposes an ECVT whereby gear ratios can be manually set in accordance with positions of a deceleration lever. Also, for example, JP-A-Sho 62-175228 proposes an ECVT whereby gear ratios can be forcibly changed or in which a shift down operation can be manually made with a switch.
However, a conventional vehicle incorporating an ECVT that is changeable between the AT and MT modes requires complicated and troublesome operations when a shift down operation is intentionally made in AT mode to accelerate or decelerate the vehicle. Specifically, in AT mode, at least the following three operations are necessary to increase or decrease vehicle speed by shifting down intentionally:
1. A switching operation from AT to MT mode.
2. A shift down operation in MT mode.
3. A switching operation from MT to AT mode.